Satellite testing of relativity (split from measuring distance to satellite)

[Bjarne]

 

But why would doing this science be a waste of money? These can do experiments that can't be done in other ways, or do them at a higher precision than other experiments.

Well noted, - and what else as plenty countless caricature and math support the curvature of space postulate?

I mean is the cause of the perihelion precision most of all a postulate or rather most of all hard evidence?

[swansont]

Well noted, - and what else as plenty countless caricature and math support the curvature of space postulate?

I mean is the cause of the perihelion precision most of all a postulate or rather most of all hard evidence?

 

Curvature of space is not a postulate, per se, it's part of the model of general relativity. There are multiple lines of evidence to support GR based on predictions it makes, including the advance of the perihelion of Mercury (which is also not a postulate). Space missions such as gravity probe B are also part of what confirms the theory. Pound-Rebka and the followup experiments.

[Bjarne]

 

Curvature of space is not a postulate, per se, it's part of the model of general relativity. There are multiple lines of evidence to support GR based on predictions it makes, including the advance of the perihelion of Mercury (which is also not a postulate). Space missions such as gravity probe B are also part of what confirms the theory. Pound-Rebka and the followup experiments.

On the one hand I understand your point of view, on the other hand I think this theory have to be verified in a proper way, - step by step.

In my universe it is not enough to conclude that when Einstein’s said A, - and indeed was correct , - then B and C are also automatically correct.

You know the best way of telling a lie, is to camouflage it with 90% truth.

The part of GR dealing with dilation is very well supported by hard evidence. I fully accept this part of the theory,

But there are problems - ultimately with quantum physics, + gravity-waves are still not yet detected.

Do you think it is impossible that one day we will have to recognize the cause of gravity was not curved space, but something else entirely?

Now we got deep enough into the rabbit hole where the last and most important question remains; -

Can you imagine that Galileo 5 and 6 may shed completely new light on exactly how a perihelion precesion anomaly is created ?

and maybe even to such an extent that we are forced to "amputate" a "upper" part of GR, ?

-------------------------------------------------------------------------------------------------------------------------------------------------------------------

There must be no barriers to freedom of inquiry. There is no place for dogma in science. The scientist is free, and must be free to ask any question, to doubt any assertion, to seek for any evidence, to correct any errors. Our political life is also predicated on openness. We know that the only way to avoid error is to detect it and that the only way to detect it is to be free to inquire. And we know that as long as we are free to ask what we must, free to say what [we] think, free to think what we will, freedom can never be lost, and science can never regress.

Robert Oppenheimer

Edited January 20, 2016 by Bjarne

[Strange]

 

On the one hand I understand your point of view, on the other hand I think this theory have to be verified in a proper way, - step by step.

In my universe it is not enough to conclude that when Einstein’s said A, - and indeed was correct , - then B and C are also automatically correct.

You know the best way of telling a lie, is to camouflage it with 90% truth.

 

Do you hav any evidence that scientific theories are not properly verified?

Do you have any evidence that GR is accepted "because Einstein said so"?

Do you have any evidence that scientists lie about their tests of GR?

 

Do you think it is impossible that one day we will have to recognize the cause of gravity was not curved space, but something else entirely?

 

Not at all. But that won't make GR wrong. In the same way that Newtonian gravity is not wrong.

[Mordred]

I have to ask Bjarnes Do you fully understand what is meant by curved spacetime? Or is your visualization based upon the common misbelief that space has a fabric like substance that can be curved stretched etc.

 

You would be amazed how few understand what spacetime curvature really represents. (Those same people are usually the ones that feel relativity is wrong).

 

So please don't be insulted, just describe what you think spacetime curvature is describing.

[Bjarne]

 

Do you hav any evidence that scientific theories are not properly verified?

 

This is what the scientific method is for, my opinion is not important

 

 

Do you have any evidence that GR is accepted "because Einstein said so"?

 

 

Yes indeed, so long serveral aspect of the theory not is verified otherwise than postulates, caricature and math (and not by observation or measurable experiments), as well as so long there are fundemental conflict with other well established science.

 

 

Do you have any evidence that scientists lie about their tests of GR?

 

Don't take all i write literally

 

 

Not at all. But that won't make GR wrong. In the same way that Newtonian gravity is not wrong.

I don't understand, if gravity is not caused by curvature of space, don't you think that aspect of the theory is wrong ?

[Mordred]

Newtonian gravity isn't wrong in everyday situations. It just doesn't work well in curved spacetime. However in Euclidean space it's just as accurate.

 

I'm still waiting on what you understand as curved spacetime.

 

By the way every aspect of relativity has been tested. Though length contraction being the least. Afiak

Edited January 20, 2016 by Mordred

[Bjarne]

I have to ask Bjarnes Do you fully understand what is meant by curved spacetime? Or is your visualization based upon the common misbelief that space has a fabric like substance that can be curved stretched etc.

 

You would be amazed how few understand what spacetime curvature really represents. (Those same people are usually the ones that feel relativity is wrong).

 

So please don't be insulted, just describe what you think spacetime curvature is describing.

I am not insulting anyone, but only skeptical to science that in fact in many cases seems not to have any grounding.

 

For years I tried to understand what is curvature of space.

Which differences would I see if I could jump from one space time reality to another?

Would the ruler at different altitude inside a gravity field always be the same? - as well as comparable the same ?

How does space curve right here at my desktop, and yes what is that curved space for kind of stuff ?

How does matter know that space curves here?

What about a 90 ton heavy CAT, is it so heavy because of the curvature of space

How is matter curving space

What happens in the process where kinetic energy is converted to relativistic mass ?

Ohh yes I have really tried, there are too many unanswered question and answer nobody really understand

, and certainly not my grandmother that Einstein once said she should.

 

Newtonian gravity isn't wrong in everyday situations.

Tell me please 3 other well grounded reasons to that Newtonian gravity is not enough other than, that Mercury have a stange orbit anomaly.

I geuss you will not

Edited January 20, 2016 by Bjarne

[swansont]

In my universe it is not enough to conclude that when Einstein’s said A, - and indeed was correct , - then B and C are also automatically correct.

 

Mine, too. The implication here is that you think this is what happened. What makes you think this? What parts, specifically, are accepted just because Einstein said so?

 

You know the best way of telling a lie, is to camouflage it with 90% truth.

 

The part of GR dealing with dilation is very well supported by hard evidence. I fully accept this part of the theory,

 

But there are problems - ultimately with quantum physics, + gravity-waves are still not yet detected.

GR is a classical theory. There is no quantum physics in it. That's a failing of a quantum theory of gravity, though. It also limits the applicability of GR, just like limitations on any other theory in science.

 

You mean gravitational waves (gravity waves are not part of GR), and we have evidence of them from the orbital changes of a binary star system.

 

Do you think it is impossible that one day we will have to recognize the cause of gravity was not curved space, but something else entirely?

 

It's possible. But as Strange has said, GR will still work where it currently works. Those calculations won't suddenly give wrong answers.

 

Now we got deep enough into the rabbit hole where the last and most important question remains; -

Can you imagine that Galileo 5 and 6 may shed completely new light on exactly how a perihelion precesion anomaly is created ?

and maybe even to such an extent that we are forced to "amputate" a "upper" part of GR, ?

No, because that would mean that the "upper" part of GR makes wrong predictions about other things, and we know that to not be the case. If it's going to stop working, it will be at a scale we haven't tested yet.

 

Tell me please 3 other well grounded reasons to that Newtonian gravity is not enough other than, that Mercury have a stange orbit anomaly.

I geuss you will not

 

 

Gravitational deflection of light by the sun. Time dilation in a gravitational potential. Shapiro delay of light. Gravitational lensing. The equivalence principle. Frame dragging.

 

https://en.wikipedia.org/wiki/Tests_of_general_relativity

[Mordred]

Ok that's roughly what I figured.

 

Lets explain spacetime curvature.

 

First let's set some ground rules.

 

You cannot measure gravity, mass etc on an empty volume. Nor energy. You must have something to measure.

 

space is nothing but volume, that happens to have the standard model particles residing in it.

 

So a gravitational field is a field of particles that we measure the influence of gravity upon.

 

Now we have to set a baseline. Well a good baseline is the average mass/energy density of the universe. Exact value isn't important.

 

We will use the Schwartzchild metric which sets this value as zero to start.

 

One final detail. Energy density of a collection of particles can cause pressure along with the particles kinetic energy.

 

Now the Einstein field equations has something called the stress/energy/momentum tensor.

 

You heard the expression "mass tells space how to curve , space tells mass how to move". Well there is a nice formula that explains this.

 

[latex]T^{\mu\nu}=(\rho+p)U^{\mu}U^{\nu}+p\eta^{\mu\nu}[/latex]

[latex]\rho[/latex]

 

[latex]T^{\mu\nu}[/latex] is the stress tensor. The subscripts are coordinates.

 

p is pressure

[latex]\rho[/latex] is energy/mass density.

 

 

https://en.m.wikipedia.org/wiki/Stress%E2%80%93energy_tensor

 

So in the presense of mass there is an influence on the gravitational field. (Particles that reside in that locality). That influence gets greater the closer to the source of mass.

 

voila spacetime curvature due to mass. Which is nothing more than the distribution curve measuring the influence of gravity upon the particles residing in a given volume.

 

It was never meant to state that spacetime was it's own fabric or mysterious substance

Edited January 20, 2016 by Mordred

[Strange]

 

This is what the scientific method is for, my opinion is not important

 

That is the process of verifying theory that you claim doesn't happen. You have just proved yourself wrong. Well done.

 

Yes indeed, so long serveral aspect of the theory not is verified

 

Can you be specific?

 

as well as so long there are fundemental conflict with other well established science.

 

You will need to be more specific about that too.

Don't take all i write literally

 

Sorry. But I will. Please apologise for accusing people of lying if you didn't mean it.

 

I don't understand, if gravity is not caused by curvature of space, don't you think that aspect of the theory is wrong ?

 

It works, therefore it is not wrong. Newtonian gravity describes it as a force. That works, in most cases, and is therefore not wrong (in most cases).

[Mordred]

On the subject of the OP. Here is a future test on The equivalence principle being launched in Apr 2016.

 

http://www.zmescience.com/science/physics/microscope-satellite-mass-equivallence-0423423/

In case it wasn't mentioned Gravity Probe B.

 

http://m.smh.com.au/technology/sci-tech/nasa-confirms-einsteins-theory-of-relativity-20110505-1e9et.html

[ajb]

I think it is true that General Relativity was taken seriously very quickly after it was proposed, largely because of Einstein who had proved himself with special relativity, and of course it has a good notion of the Newtonian limit. The only decent confirmation of general relativity as being a good theory was made in the 1960s with technological advances. So, today GR is very well tested to so some stupid degree of accuracy on par with the standard model of particle physics. Anyone interested should look at Clifford Wills paper in Living Reviews of Relativity.

[Bjarne]

I think it is true that General Relativity was taken seriously very quickly after it was proposed, largely because of Einstein who had proved himself with special relativity, and of course it has a good notion of the Newtonian limit. The only decent confirmation of general relativity as being a good theory was made in the 1960s with technological advances. So, today GR is very well tested to so some stupid degree of accuracy on par with the standard model of particle physics. Anyone interested should look at Clifford Wills paper in Living Reviews of Relativity.

Which evidence are there fore Newtonian limits, I am not sure I is awre of all

[ajb]

Which evidence are there fore Newtonian limits, I am not sure I is awre of all

You can show that Newtonian gravity comes out as a kind of limit of general relativity. This is general relativity 101, surely you know this if you are looking at tests of general relativity?

[Bjarne]

Mine, too. The implication here is that you think this is what happened. What makes you think this? What parts, specifically, are accepted just because Einstein said so?
GR is a classical theory. There is no quantum physics in it. That's a failing of a quantum theory of gravity, though. It also limits the applicability of GR, just like limitations on any other theory in science.

 

Take a watch , good quality video https://www.youtube.com/watch?v=_mQhZB5lmvk

You mean gravitational waves (gravity waves are not part of GR), and we have evidence of them from the orbital changes of a binary star system.

Yes this is what I mean, - Well energy loss has been detected, - not gravitational waves. Energy loss can be explained by different theories.

 

It's possible. But as Strange has said, GR will still work where it currently works. Those calculations won't suddenly give wrong answers.

So long it doesn’t become a holy cow, - fine

 

 

No, because that would mean that the "upper" part of GR makes wrong predictions about other things, and we know that to not be the case. If it's going to stop working, it will be at a scale we haven't tested yet.

 

I really don’t understand why so many people think that the theory of relativity is everything or nothing. Already in the late 1800 it was known that the consequence of the Lorentz Equation meant that time dilation was a consequence, but no one except Einstein took that serous. Einstein begun to implement these already known consequences, - in a new overall picture of the world.

The point is that you can implement the consequences of the Lorentz transformation in a different way, - it will not be the end of the world. It all depend on which experiments supports you , and which aspect of science could have been misunderstood, or poorly understood.. And therefore my point is maybe a modification of the of relativity can soon be justified, - and even without the GPS systems stop working.

Gravitational deflection of light by the sun. Time dilation in a gravitational potential. Shapiro delay of light. Gravitational lensing. The equivalence principle. Frame dragging.

 

https://en.wikipedia.org/wiki/Tests_of_general_relativity

 

Well, it all tells about the property of space, but it doesn’t prove that the cause of gravity is curvature of space. – There is a huge gap / lack of evidence here.

A modified theory of relativity could maybe answer what relativistic energy really is and why gravitational waves, - never are detected, - and even unite Relativity and Quantum mechanics..

Nerver say never

 

You can show that Newtonian gravity comes out as a kind of limit of general relativity. This is general relativity 101, surely you know this if you are looking at tests of general relativity?

 

I would have preferred if you had answered the question

Which evidence are there for Newtonian limits, I am not sure I is aware of all..

[Strange]

I would have preferred if you had answered the question

Which evidence are there for Newtonian limits, I am not sure I is aware of all..

 

That is a different question. It was known that Newtonian gravity was not accurate even when Einstein was developing the theory (which, I have read, was part of his motivation). The anomalous precession of Mercury is the usual example.

http://physics.ucr.edu/~wudka/Physics7/Notes_www/node98.html

 

Since then, other areas where the Newtonian theory is wrong have been found. One of the earliest was the difference in the amount of gravitational lensing predicted.

[ajb]

Yes this is what I mean, - Well energy loss has been detected, - not gravitational waves. Energy loss can be explained by different theories.

Can you point to these other theories?

 

Predictions based on general relativity and in particular gravitational waves, seems to fit the observes loss of energy.

 

 

I would have preferred if you had answered the question

Which evidence are there for Newtonian limits, I am not sure I is aware of all..

 

I am not quite sure what you mean by evidences for the Newtonian limit, other than Newtonian gravity works quite well in a lot of situations. For example, Newtonian gravity is enough to plan a space-flight to the Moon.

 

As for deriving the Newtonian limit see (for example) chapter 4 of the lecture notes by Carroll, or any other introductory text to general relativity. I think there is little point in reproducing the arguments here, unless you have a specific question which maybe better off in another thread.

 

Anyway, the point is that as we know that Newtonian gravity can be derived as a limit of general relativity nothing in general relativity 'goes against' Newtonian gravity. This is important when proposing new theories, they should not contradict established and well tested theories.

 

Since then, other areas where the Newtonian theory is wrong have been found.

It is a subtle issue to exactly what one means by 'wrong', but okay. It is true that general relativity covers a wider range of gravitational phenomena than Newtonian gravity. However, the two are not really in conflict as we can understand Newtonian gravity as a limit of GR.

 

It is a quite analogous to comparing electrostatics (Coulombs law etc) to Maxwell's equations. Coulombs law works great for a range of phenomena, but Maxwell's equations are really needed for a wider understanding of electromagnetic theory.

[Strange]

It is a subtle issue to exactly what one means by 'wrong', but okay.

 

Indeed. I should have said "inaccurate", especially as I have said elsewhere that Newtonian theory is "not wrong"!

[Bjarne]

Can you point to these other theories?

 

If we can meet a dark place, no problem

In the meantime have you ever thought about what is relativistic mass / energy really (made of) ?

And what do you think happens in the process where kinetic energy is converted to mass / energy ?

Furthermore, gravitational energy, where is that.

I know we have a worrd / expression for that energy, can you piont to where is the energy, - you know E (convertible with M) ?

 

I am not quite sure what you mean by evidences for the Newtonian limit, other than Newtonian gravity works quite well in a lot of situations. For example, Newtonian gravity is enough to plan a space-flight to the Moon.

 

As for deriving the Newtonian limit see (for example) chapter 4 of the lecture notes by Carroll, or any other introductory text to general relativity. I think there is little point in reproducing the arguments here, unless you have a specific question which maybe better off in another thread.

 

Anyway, the point is that as we know that Newtonian gravity can be derived as a limit of general relativity nothing in general relativity 'goes against' Newtonian gravity. This is important when proposing new theories, they should not contradict established and well tested theories.

 

 

It is a subtle issue to exactly what one means by 'wrong', but okay. It is true that general relativity covers a wider range of gravitational phenomena than Newtonian gravity. However, the two are not really in conflict as we can understand Newtonian gravity as a limit of GR.

 

It is a quite analogous to comparing electrostatics (Coulombs law etc) to Maxwell's equations. Coulombs law works great for a range of phenomena, but Maxwell's equation

 

 

We have more to learn more about gravity, much more, - and also how energy and space get involved with each other.. I think you will agree to that.

Edited January 21, 2016 by Bjarne

[ajb]

If we can meet a dark place, no problem

Meaning you cannot point to published papers that explain the energy loss of binary systems that do not use gravitational radiation? If so, then what the heck are you talking about?

 

In the meantime have you ever thought about what is relativisetic energy really is (made of) ?

Not really... energy is a property of a physical configuration. It is not a 'thing' itself. Now, of course, defining energy in GR is a bit subtle, but that does not seem to be related to your, frankly awful question.

 

And what do you think happens in the process where kinetic energy is converted to mass / energy ?

You will need to ask much more specific questions than that to get meaningful answers. What are you hinting at here?

 

Furthermore, gravitational energy, where is that.

Do you mean gravitational potential energy as in Newtonian theory, or the energy (mass) of a given space-time or the energy-momentum tensor of gravitational radiation? (the latter is problematic, and worth a discussion else where.)

 

 

Your questions suggest you need to revise basic physics of energy, from there we can discuss more subtle issues in relativistic theories.

[Bjarne]

Meaning you cannot point to published papers that explain the energy loss of binary systems that do not use gravitational radiation? If so, then what the heck are you talking about?

 

 

Not really... energy is a property of a physical configuration. It is not a 'thing' itself. Now, of course, defining energy in GR is a bit subtle, but that does not seem to be related to your, frankly awful question.

 

 

You will need to ask much more specific questions than that to get meaningful answers. What are you hinting at here?

 

 

Do you mean gravitational potential energy as in Newtonian theory, or the energy (mass) of a given space-time or the energy-momentum tensor of gravitational radiation? (the latter is problematic, and worth a discussion else where.)

 

 

Your questions suggest you need to revise basic physics of energy, from there we can discuss more subtle issues in relativistic theories.

Let's make all this short, the point is so long that gravitational waves are not detected , but energy loss is a fact, - we have indeed a big problem , because where does that energy go ?

How can energy vanish undetected?

I believe this is a serious question we sooner or later is forced to consider.,

Right now such thought is forbidden because of the holy theory of relativity

I think time is not correct, let LIGO and gravitational waves ideas cool down the next couple of years, then we can take a talk. Or if you wish start a thread at speculation and I can put a few very noisy flies in your head.

Edited January 21, 2016 by Bjarne

[ajb]

Let's make all this short, the point is so long that gravitational waves are not detected , but energy loss is a fact, - we have in deed a big problem , because where does that energy go ?[/size]

Indeed, so far there has been no direct detection of gravitational waves. They have been implied by careful study of this energy loss. That is the energy loss is quite consistent with that expected to be carried away by gravitational radiation.

 

 

How can energy vanish undetected?[/size]

Easily if we cannot detect what is carrying away this energy.

 

 

I believe this is a serious question we sooner or later is forced to consider.,[/size]

In the context we are discussing it is a serious question. And one that is solved in the context of gravitational radiation, but we all accept that some other explanation would be needed if gravitational radiation is not realised in nature. So right now, the best explanation we have is that gravitational radiation carried away this energy.

 

I am not aware of any other explanations.

 

Right now such thought is forbidden because of the holy theory of relativity[/size]

Absolute rubbish. If you have a theory that explains this energy loss and does not invoke gravitational radiation then please publish it. People will be very interested.

 

I think time is not correct, let LIGO and gravitational waves ideas cool down the next couple of years, then we can take a talk. Or if you wish start a thread at speculation and I can put a few very noisy flies in your head. [/size]

What do you mean by 'time not correct'? You mean time dilation effects that have be confirmed over and over again?

 

Being quite blunt, given some of your questions here, I am not convinced of these flies!

[Strange]

Let's make all this short, the point is so long that gravitational waves are not detected , but energy loss is a fact, - we have in[/size]deed a big problem , because where does that energy go ?[/size]

 

We don't (yet) have a big problem because it is known that current experiments are very unlikely to detect anything (because they are not really sensitive enough). There is, no doubt, some limit of sensitivity at which it would become a "big problem" - or, as scientists tend to think of it, a massive and very exciting opportunity to discover new physics.

 

How can energy vanish undetected?

 

Because we are not yet able to detect it. This is hardly an unprecedented situation. It was several years after the missing energy in beta decay was spotted before neutrinos could be detected.

 

I believe this is a serious question we sooner or later is forced to consider.

 

It is being considered.

 

Right now such thought is forbidden because of the holy theory of relativity

 

Nonsense. The way for a scientist to become world famous (hailed as "the new Einstein") and win a Nobel Prize would be to show that GR is wrong.

 

Don't let your emotional dislike of the theory get in the way of rational discussion.

[swansont]

Take a watch , good quality video https://www.youtube.com/watch?v=_mQhZB5lmvk

A video that points out the GR is classical and not quantum, and places limits on it, just like any theory. But it doesn't address the question. You implied there are parts of GR which are accepted just because Einstein said so. What are they?

 

 

Yes this is what I mean, - Well energy loss has been detected, - not gravitational waves. Energy loss can be explained by different theories.

What are these other theories?

 

I really don’t understand why so many people think that the theory of relativity is everything or nothing. Already in the late 1800 it was known that the consequence of the Lorentz Equation meant that time dilation was a consequence, but no one except Einstein took that serous. Einstein begun to implement these already known consequences, - in a new overall picture of the world.

The point is that you can implement the consequences of the Lorentz transformation in a different way, - it will not be the end of the world. It all depend on which experiments supports you , and which aspect of science could have been misunderstood, or poorly understood.. And therefore my point is maybe a modification of the of relativity can soon be justified, - and even without the GPS systems stop working.

I don't know who these "many people" are, but nobody in this thread has said that relativity is all-or-nothing. If you can find an experimental reason to modify relativity, show it to us. If you have such a modification, present it. You mention the Lorentz transforms having different consequences, but you stop short of saying precisely what these are. IOW, all blather and no science.

 

Well, it all tells about the property of space, but it doesn’t prove that the cause of gravity is curvature of space. – There is a huge gap / lack of evidence here.

A modified theory of relativity could maybe answer what relativistic energy really is and why gravitational waves, - never are detected, - and even unite Relativity and Quantum mechanics..

Nerver say never

Not even an acknowledgement that you lost the bet?

 

I would have preferred if you had answered the question

Which evidence are there for Newtonian limits, I am not sure I is aware of all..

Given your predilection to avoiding answers, this is ... interesting. I think we all prefer that you answer the questions, too.

 

In the meantime have you ever thought about what is relativistic mass / energy really (made of) ?

And what do you think happens in the process where kinetic energy is converted to mass / energy ?

 

Irrelevant to the current discussion. Relativity only says that mass is a form of energy.